mantis (original) lens - I want to make one

[sreeb]

I have a mantis that came with only a 6x lens.  I want a second lens in the 2x-3x range.

The ones I see on ebay are all in poor condition, very expensive, or both.

From pictures, these appear to be a very simple single element design.  It looks like it should be easy to copy one if I can scrounge an element.

I have a lathe and a 3d printer.  I think building one should be reasonable project.

However I don't have one to copy or any information on the optical path in the head.

Is there anyone out there who could measure one for me?

I'm looking for the focal length and the distance between the element and threads on the head.

Since all I know about optics is what I recall from high school many years ago, I'm open to suggestions on the design.

Ed

[Pinkus]

I cannot help with the technical details your are asking for, but look here:
https://www.thingiverse.com/thing:222849
and here:
https://www.thingiverse.com/thing:1330221
This might help you designing your own.
But be warned: I tried the above myself and the picture quality was not satisfying at all. You definitely need to use lens with a larger diameter.
The original 2x lens often can be purchased used for $20-30 if you are lucky. Usually you can ignore scratches on the lens as they are invisible later when using the Mantis.